Conventionally, an air-conditioner for a vehicle heats air inside of a passenger compartment by using waste heat of the engine as a heat source. Moreover, a temperature of conditioned air can be set individually for a driver-side space and a passenger-side space to raise the comfortableness of the passenger compartment. In such the air-conditioner, a heat amount required for the heating operation is obtained through a heater core, and unnecessary heat is radiated out of the vehicle through a radiator.
However, waste heat of the engine is insufficient in an electric car. JP-A-7-1954 (U.S. Pat. No. 5,537,831) describes an air-conditioner which performs cooling operation and heating operation using a heat pump refrigerating cycle.
In the heat pump refrigerating cycle, flow rate of refrigerant is controlled by controlling rotation speed of a compressor so that the amount of heat released into the passenger compartment is controlled. The air-conditioner of JP-A-7-1954 does not have a heat exchanger which radiates heat out of the passenger compartment.
In the above-mentioned air-conditioner using waste heat of the engine, in a case where the temperature control is performed independently between the driver-side space and the passenger-side space (hereinafter referred as independent control), the heat release amount is controlled by controlling each air mix (AIM) door, and excess heat is radiated out of the passenger compartment from the radiator.
In contrast, in the case of the heat pump refrigerating cycle, the independent control cannot be realized only by controlling the air mix door. For example, if the preset temperature is lowered on the passenger-side space from the state where the same temperature is set for the driver-side space and the passenger-side space, the amount of heat used for heating the passenger compartment is reduced. In this case, if the air amount is reduced for the passenger-side space only by controlling the air mix door, the heat release amount is increased on the driver-side space, and the amount of heat used for heating the passenger compartment does not change.
Then, it becomes an object, for the air-conditioner using the heat pump refrigerating cycle, to achieve the independent control by changing the amount of heat used for heating the passenger compartment.